


Brothers

by LuminousGloom



Category: Harry Potter - J. K. Rowling
Genre: Accidental Voyeurism, Anal Sex, Blow Jobs, M/M, Marauders' Era, Oral Sex, Secret Crush, Sex, Sexual Fantasy, Sibling Incest Fantasy, Sirius Black & James Potter Friendship, Smut, Voyeurism
Language: English
Status: Completed
Published: 2018-11-03
Updated: 2018-11-03
Packaged: 2019-08-03 05:53:51
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,344
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16320350
Author URL: https://archiveofourown.org/users/LuminousGloom/pseuds/LuminousGloom
Summary: Regulus can't get enough of watching his big brother.Written forSirius Black Fest 2018





	Brothers

**Author's Note:**

> **Prompt #:** [43](https://sirius-blk.dreamwidth.org/308005.html?thread=1048357#cmt1048357) by shaggydogstail: _Regulus can't get enough of watching his big brother._  
>  **Disclaimer:** Harry Potter characters are the property of J.K. Rowling and Bloomsbury/Scholastic. No profit is being made, and no copyright infringement is intended.  
>  **A/N:** A big Thank You! to E and S for beta reading  & your excellent input.

** Shower **

Regulus suppressed a gasp. He wasn’t going to let on just how much he relished the sight of Leonide Zabini on his knees before him, just how expertly the other boy was taking him apart. They’d done this a couple of times before, but never here in the Quidditch pavilion, where they might actually be discovered.

Zabini maintained an air of haughty indifference, even while sucking him off like a young god. But so very keen, Regulus thought smugly. Given half a chance, Zabini would be back for more. Resting his hand on the back of the sleek bobbing head, he bucked his hips, shoving his cock deeper down the other boy’s throat. Zabini made a muffled sound, but went with it.

Both of them froze at the sudden crash as the door to the changing area was thrown open. What must be the Gryffindor team came barging down the corridor, shouting and laughing. Grinning now, Regulus lazily pushed into Zabini’s mouth again, urging him to carry on. Zabini didn’t need telling twice. They were unlikely to be seen, hidden as they were behind dusty sports equipment in the dark store room. Through the half open door Regulus could see across the corridor and into the showers.

The Gryffindor house team were being ridiculously loud. Regulus held his breath as several players in their underwear ambled past. Briar and Moore and Atkinson, making a racket, slapping each other with towels. If only they knew! Regulus thought deliriously, suppressing a low moan as Zabini gripped the base of his cock while eagerly tonguing the slit.

Then two more players appeared, laughing and jostling each other. One of them moved on rapidly, probably that idiot Potter. The other one lingered, and even though Regulus only saw him from behind, of course he recognised him at once. Tall and lean, moving with casual nonchalance. The same dark hair as Regulus’ own.

Regulus hadn’t seen his brother like this, not since they’d been much younger. He watched as Sirius carelessly discarded his boxers and stepped into the one tiled cubicle half in Regulus’ field of vision, before reaching out, apparently turning on the tap. Zabini was cupping Regulus’ balls now, squeezing them a little as he went to town on his cock. Regulus exhaled slowly, deeply, trying not to come.

He was still watching Sirius. Watching the subtle play of muscles as his brother shifted and turned under the streaming water. Watching him reach out of sight for some sort of soap before proceeding to lather himself up.

Gripping the back of Zabini’s head more fiercely, Regulus bucked his hips again. He pushed into Zabini, his gaze fixed on his brother. Fucking that wet, willing mouth as his eyes followed the flecks of foam sliding down his brother’s strong shoulders, down that glistening back, past narrow hips, and into the crack of that tight, pale arse.

“Oh!” Regulus choked out, pulling back. Zabini didn’t miss a beat and switched to furiously wanking Regulus’ cock. Across the corridor, Sirius was stretching up, blithely rinsing his hair, as Regulus screwed his eyes shut and came.

 

** Hogsmeade **

“Go on in, I’ll wait outside.” Regulus told Selwyn and lit one of the thin black cigarettes he was trying out. Suppressing his urge to cough, he exhaled a plume of purple smoke and casually gazed into the distance.

He could see Sirius and his bosom buddy, Potter, perched on a stone wall, as though waiting for someone or something. Sitting close together, talking earnestly. There was something odd about all of them, his brother’s three weird friends. An aura of secrecy. And, he thought, looking at Sirius and Potter now, a whiff of intimacy.  
What if there was more between them? Perhaps they secretly got off together when no one was looking?

He pictured them together, in his vague idea of what their Gryffindor dormitory looked like. Hiding behind red bed curtains in a creaking four poster. Snogging impatiently, groping each other through their clothes, unbuttoning each other’s trousers...

Still huddled together, Sirius and Potter were laughing now. They probably did wank together. Everyone was doing it. Perhaps the other two - their short, buck toothed mate, and the other one - got in on it, too. Maybe they all got together of an evening, whipping their cocks out, sucking each other off. Or what if -

Inhaling another lungful of purple smoke, Regulus couldn’t help picturing his brother lying prone on his stomach, panting and moaning as Potter’s prick pushed into him. Potter gripping those narrow hips and pounding Sirius’ arse, that same arse Regulus remembered so vividly from the other day. Or maybe Sirius would have had Potter pinned beneath him, fucking him hard and fast, making Potter whine and beg...

Regulus cleared his throat and adjusted his trousers beneath his robes. Sirius’ two other friends had turned up, and they were talking and gesturing animatedly. Regulus could not fathom what his brother saw in any of those losers. Then Potter and Bucktooth started up the road towards him, while Sirius and the other one lingered, beaming at each other.

“Ouch!” Dropping the cigarette end that had singed his finger, Regulus burst into a coughing fit.

The shop-bell tinkled, and Selwyn appeared. “All right, Reg? We’ve got everything. Even your roasted Dragon Scales. You coming?”

 

** Dream **

The strange thing was, in his dream, Sirius was so gentle. They weren’t fighting, in fact they ended up kissing. And Sirius’ large, elegant hands were touching him easily, in a matter of fact sort of way. Regulus leaned in, and Sirius, knowing that his younger brother would be hard, placed his palm firmly on Regulus’ crotch.

 

** Lunch **

In the Great Hall, Regulus let his gaze wander. Pretending to eye various girls. Winking at Gerard Hooke in the year below, who grinned at him nervously and then remembered to act aloof. Glancing at the numbskulls over at Gryffindor table.

Sirius was talking not to Potter or Bucktooth, but the other one. Lupin. Formerly awkward and sort of scrawny looking, there was something arresting about that boy, not that Regulus would touch him with a bargepole. Sirius was grinning, listening to Lupin intently.

He always seemed to be laughing these days, always in high spirits. Regulus couldn’t work it out. He knew Sirius had had a letter from home, things were looking pretty dreadful.

Regulus had never understood why his brother had to be so damned contrary. Constantly trying to defy their parents, always causing conflict, just to be “different”. It didn’t make any sense. Regulus was proud of his family heritage, proud of their traditions and social standing. He felt honoured to fulfil his obligations. Sirius insisted on having everything his own way.

Next to Sirius, Potter was childishly sparring with Bucktooth and two other blokes, all of them firing jinxes at each other between bouts of laughter. There was a puff of smoke, from which Potter emerged sporting a dragon’s snout. Ever the show off, he actually spat fire, albeit a rather puny amount. Still, his moronic friends laughed and applauded. Except for Sirius and Lupin, who didn’t even seem to have noticed. Potter wasn’t going to like that, Regulus thought, gleefully predicting trouble in paradise.

 

** Distraction **

He’d not really understood why Vaughan Balfour kept harassing him. Cocky, annoying, devastatingly handsome, the Seventh Year Ravenclaw had started waylaying him, mocking and taunting him for no apparent reason. Once or twice he’d even seized Regulus and tried to throw him to the floor. Until now. On the way to lunch in the Great Hall, Balfour shoved into him, pushing him behind a tapestry, against the rough wall. Drawing his wand in defense, Regulus felt Balfour’s hot breath on his neck, and Balfour’s hand on his crotch.

They met later that evening. As much as Vaughan was determined, Regulus was keen to learn. In the dim empty classroom, Balfour showed him a lubrication spell, and proceeded to shag him energetically. Regulus liked it. Having pulled out and come all over Regulus’ lower back, Balfour laughed and playfully slapped the younger boy’s arse. “And that’s the other Black brother. Now I’ve had the set.”  
Regulus liked that even more.

 

** Brothers **

One morning two summers ago, Regulus was in their shared bathroom at home, brushing his teeth, when Sirius rushed in, unwilling to wait for his shower. As he stripped off and disappeared behind the shower curtain, Regulus caught a glimpse of Sirius’ cock in the mirror. He was stunned by its size. He’d not seen it since he was little, back when they’d been made to share baths. His own member was nothing like that yet. He’d only just begun to grow pubes.

Now, Regulus couldn’t help returning to the Quidditch changing rooms again and again. With Zabini, and alone, too. Hoping to catch another glimpse, although he told himself that he liked to see the team strip. He did enjoy watching various other players, too, parading around practically naked, and prancing into the showers, but none of them quite did the trick. He didn’t get to see Sirius again.

It wasn’t all that odd, he told himself. After all, wild rumours circulated about the Bulstrode twins, who’d graduated the previous year, and now apparently shared more than just a flat in Salford. When Selwyn had told him about their antics in gleeful outrage, Regulus had made a face, too. Mainly because imagining the Bulstrode boys in any state of undress effectively ruined what would otherwise be a titillating fantasy.

Of course he met up with Balfour again, whose escapades with Sirius had been much on Regulus’ mind. When he asked if he was planning to pursue his cousins next, Balfour snorted, saying he wasn’t that desperate. Regulus wanted to ask about Sirius, about what they’d done, but somehow didn’t manage. He let Balfour shag him again, and let his imagination run free.

 

** In Bed **

He tried not to think about him, late at night, tried to banish all thoughts of his brother. Which somehow only made them more enticing. Sirius’ pale backside. Sirius’ haughty demeanour, as he’d lean over a desk, provocatively sticking out his bum. Belittling him, even as Regulus would slide his lubed up boner along Sirius’ crack. Gasping despite himself as Regulus pushed in. And then, Regulus would fuck him, the desk rocking with every thrust, Sirius grunting and moaning, panting, and begging for more.

Regulus, wanking furiously, imagined coming in his big brother’s arse. Sirius would turn his head to smirk at him then, smug, and satisfied. Perhaps he’d raise an eyebrow and wink at him.

 

** Potter **

Regulus noticed Sirius in the library, for once sitting all by himself. Surrounded by stacks of books and scowling at his homework. Later, Regulus saw him laughing with Bucktooth near the greenhouses. Again, Potter wasn’t there. And yet another time, he spotted Sirius and Lupin sauntering towards the lake, with Potter nowhere to be seen. And Potter had moved seats at mealtimes. Had they had a fight? The idea pleased Regulus no end.

He’d always disliked Potter, who irritated him more than any other of his brother’s dumb Gryffindor friends. Too bloody full of himself, for one thing, and too - possessive. Back when he’d first started at Hogwarts, Regulus had been surprised to find that this boy Potter had attached himself to Sirius like a leech.

Well, as it turned out, Potter could stick his romantic ideas about loyalty, his ridiculous talk of blood brothers and all that rubbish. Best of all, Regulus noted smugly, Sirius didn’t even seem that bothered, by all appearances he remained unmoved that they’d fallen out. Didn’t mean all that much to him.

But then, just before the inter-house match, Regulus realised his mistake. Gryffindor were playing Ravenclaw, and he recognised Potter, already in his team robes, snogging some girl by the Quidditch pavilion. When Sirius and Briar emerged from the changing rooms, Sirius casually flicked some sort of jinx at Potter. Chinese Burn probably, which Regulus knew only too well his brother was fond of. Potter whipped around angrily, then laughed when he saw the culprit. Sirius, grinning now, slowed his step as he passed Potter. They clapped each other on the back, exchanging a few words and a meaningful look. Still beaming, Potter returned to snogging his girlfriend.

 

** At Night **

Under the cover of a Disillusionment Charm, Regulus moved silently through the dimly lit corridors. This part of the castle was very quiet, he could barely hear the music and excitement emanating from the raucous party up in Ravenclaw Tower. The door to the empty classroom gaped open, and he slipped inside, keeping to the shadows.

“Ah! There you are,” a young male voice said in the dark. Regulus froze. Sirius spoke again, in a teasing tone. “I’ve been expecting you.”

It really was Sirius. Regulus could just about make him out, silhouetted against one of the windows. Not moving a muscle, Regulus felt his heart thumping in his throat, while his mind raced, trying to work out what to say, how to play it.

There was a low chuckle, as another figure melted out of the darkness. “Hello.” Regulus didn’t immediately recognise the voice. “Lumos,” the figure said quietly, and the pale wandlight revealed him to be that other friend. Lupin.

Lupin had walked right up to Sirius. Regulus watched as the boy brought his hands up to Sirius’ face and nonchalantly pulled him into a kiss. Regulus’ jaw dropped. Sirius was kissing Lupin, snogging him. Passionately. Regulus saw Sirius’ hands trailing down Lupin’s back, one slipping beneath Lupin’s shirt, the other moving even lower, groping his bum.

Transfixed, Regulus was unable to do anything but stare. He felt winded. And somewhat crushed, but oddly relieved, too, that he didn’t have to explain himself. So his brother did actually like boys! And liked them a lot, by the looks of it. Or at least this one.

When Sirius let out a low moan and Lupin bucked his hips into him, Regulus began to fervently hope that Balfour wouldn’t show up after all. They’d been vague about meeting here, just a raised eyebrow and a shrug at the Ravenclaw party. Funny Sirius should’ve chosen this very room as well, as though it was the only empty classroom in the castle. Not that Regulus minded. He wondered why they didn’t just use their own dormitory. Perhaps it was already occupied.

Still snogging, they’d started moving in a slow rhythm, rutting against each other. They came apart, mumbling words, laughing quietly. Then there was the clinking of a belt buckle. “Yeah,” Lupin said rather breathlessly, and Sirius firmly tugged down Lupin’s trousers. Taking a few steps backwards, Lupin perched on a desk.

 _Yes,_ Regulus thought, as Sirius dropped to his knees.  
Lupin’s lit wand clattered to the floor and rolled away across the flagstones. Leaning back, his hands braced on the desk, Lupin watched Sirius’ head bobbing up and down, lapping at Lupin’s cock, slurping, devouring it. The moon, large and round, shone like a lamp through the window, illuminating the scene in all its glory.

Watching intently, Regulus started to grope and fondle his own bulging erection. Sirius looked amazing, entirely dedicated to the task of sucking cock. Lupin’s hand at the back of his head, pushing him down, urging him on. Fucking his mouth, Regulus thought, managing to suppress a small moan.

It ended all too soon, when Lupin made a gruff sound and pushed Sirius’ head away. Regulus froze. Was the Charm holding up? With the moon shining so bright, would they spot him if they looked his way?

He needn’t have worried, though. Because they weren’t done yet.

They were kissing again, Lupin had kicked off his shoes and trousers and reeled Sirius in, his bare legs on either side of Sirius’ body. Snogging him hungrily, Lupin was making short work of Sirius’ trousers. He seemed very forthright, and demanding, which vaguely surprised Regulus, then again he really didn’t know very much about that boy at all. And this certainly wasn’t the first time they’d done things together.

“Take off your shirt,” Lupin said. Laughing softly, Sirius obliged, while Lupin took obvious pleasure stripping him of his boxers, squeezing Sirius’ pale arse. Then he got hold of Sirius’ cock. Regulus swallowed hard. His mouth had gone dry. Sirius huffed, bucking his hips. Lupin mumbled something, and Regulus thought he could hear the slick sucking sound of lube. Merlin.

They kissed once more. “Go on then,” Lupin’s voice sounded ragged. “I want you. Fuck me, Pads.”

Regulus didn’t catch Sirius’ reply, his heart was thumping wildly, his own cock already leaking into his pants. Vaguely wondering what their stupid nicknames were even supposed to mean, he decided he needed a better view. He took a few silent steps, fiercely controlling his breathing.

After another searing kiss, Sirius pushed Lupin onto his back and lifted his thighs. Lupin pulled them up toward his chest, spreading them wantonly. He really couldn’t wait.

Sirius ran a finger down Lupin’s crack, while fondling Lupin’s balls with his other hand. Sirius looked magnificent in the moonlight, that arse, his muscular back, his strong arms and defined chest...

Regulus stared, and silently gasped. Because there was Sirius’ cock - large, standing proud, gleaming with lube. Strangely familiar looking, too. And magnificent.

Mesmerised, he fiercely kept working his own cock. His mind reeled with ideas, visions of things he’d like to do, if only he were allowed to touch that thing, to…

Meanwhile, Sirius dragged the tip of his cock along Lupin’s crack, nudging him. When he pushed in, Lupin moaned with delight. Sirius stilled for a moment, exhaling audibly.

Then he began to fuck him.

Sirius’ hips moved smoothly, in a brisk, steady rhythm. Regulus could hear Sirius panting. He didn’t dare go any closer, but he wished he could actually see the glistening shaft pistoning in and out, going balls deep into Lupin, fucking him, reducing the strange boy to muffled sounds of pleasure.

Really though, he was picturing himself being fucked like that, firmly and vigorously. That big cock pounding into him, taking him. Regulus would be moaning with every thrust, desperate for more. He’d let Sirius ravish him. He’d let his big brother fuck his arse until he pumped him full of come.

Regulus bit into the heel of his thumb so as not to cry out. Sirius pulled out, helped Lupin turn over so he was now bent over the desk, and plunged right back in. Dazed, still trying to calm his breathing, Regulus watched in awe as Sirius continued to shag his friend, hard and fast now. He slowed only briefly, leaning in and turning Lupin’s face towards him for a passionate kiss, before carrying on at pace.

Lupin, panting hard, sort of growled when he came. Sirius pulled out and fiercely pumped his cock, decorating Lupin’s ravaged arse and lower back with shiny splashes of come.

Regulus’ own pants felt cold and uncomfortably sticky, but he decided it was safer to stay put and let them leave first. Sirius and his friend got dressed, chatting blithely about random things, and snogging yet again. When they left, Regulus thought they might have been holding hands.

 

The following morning on the way to breakfast, Vaughan Balfour elbowed Regulus just outside the Great Hall.

“Sorry about last night.” Balfour looked decidedly worse for wear. “Not sure what happened, got a bit - carried away.” He yawned.

Regulus shrugged haughtily. “I was busy anyway. Something else came up.”

“Get your end away after all, did you?” Balfour grinned lasciviously.

“Well...” Just then, Sirius rounded the corner, Lupin in tow. They weren’t holding hands now. Both of them were looking fresh, and rested, and in high spirits. They’d probably just had a shower, his mind supplied unnecessarily, along with some tantalising imagery.

Randomly glancing his way, Sirius found his brother staring. He raised an eyebrow at Regulus. Looking over his shoulder as he walked on into the hall, Sirius added a quizzical smirk. And a wink.


End file.
